Vehicles can utilize electric fraction motors to drive wheels. In such case, a vehicle may include a three-phase alternating current (AC) motor coupled to a power inverter. The power inverter converts direct current (DC) from a power source to alternating current that can be used by the AC motor. Typically, the power inverter includes components, such as insulated gate bipolar transistors (IGBTs) and a direct bonded copper (DBC) substrate. The IGBTs act as switches used in converting the power from DC to AC and are mounted on the DBC substrate. The DBC substrate includes integrated bus bars that may be combined with a circuit card and a signal connector to provide a power electronics package for the vehicle.
As the vehicle starts, changes cruising speeds, accelerates and/or brakes, power demands of the electric traction motor driving the vehicle may fluctuate over a relatively wide range (e.g., in a range of from about 5 kW and about 120 kW). These power demand fluctuations may cause temperature changes in the power inverters during operation. Over time, the operability of the power inverter may degrade due to the temperature changes. Specifically, because IGBTs and DBCs may be made of different materials, they may expand and/or contract at different rates and thus, may shift positions relative to each another.
To limit the expansions and contractions of the power inverter components to a selected range, the temperature changes within the power inverter may be controlled. For example, the power inverter may include a cooling system that provides fluids that are circulated through heat sinks associated with the DBC substrate. In other instances, air may be directed over the power electronics package to absorb and remove heat from the DBC.
Though the aforementioned configurations have been generally sufficient for cooling the power inverter components, they may be improved. For instance, the aforementioned configurations may be relatively heavy and may not be suitable for inclusion into vehicles having weight restrictions. In other cases, the aforementioned configurations may have a relatively large footprint and may not be useful for inclusion into small vehicles. In still other cases, the heat sink may not remove heat from the DBC substrate as efficiently as desired.
Accordingly, it is desirable to have a power inverter that has a cooling system that is more lightweight and/or smaller in size than conventional inverters. In addition, it is desirable for the power inverter to be relatively simple and inexpensive to manufacture. Moreover, it is desirable for the cooling system to be suitable for inclusion into a variety of different space configurations within different types of power inverters. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.